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/****************************************************************************
* drivers/power/pm_activity.c
*
* Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/power/pm.h>
#include <nuttx/clock.h>
#include <arch/irq.h>
#include "pm_internal.h"
#ifdef CONFIG_PM
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pm_activity
*
* Description:
* This function is called by a device driver to indicate that it is
* performing meaningful activities (non-idle). This increments an activity
* count and/or will restart a idle timer and prevent entering reduced
* power states.
*
* Input Parameters:
* priority - Activity priority, range 0-9. Larger values correspond to
* higher priorities. Higher priority activity can prevent the system
* from entering reduced power states for a longer period of time.
*
* As an example, a button press might be higher priority activity because
* it means that the user is actively interacting with the device.
*
* Returned Value:
* None.
*
* Assumptions:
* This function may be called from an interrupt handler (this is the ONLY
* PM function that may be called from an interrupt handler!).
*
****************************************************************************/
void pm_activity(int priority)
{
uint32_t now;
uint32_t accum;
irqstate_t flags;
/* Just increment the activity count in the current time slice. The priority
* is simply the number of counts that are added.
*/
if (priority > 0)
{
/* Add the priority to the accumulated counts in a critical section. */
flags = irqsave();
accum = (uint32_t)g_pmglobals.accum + priority;
/* Make sure that we do not overflow the underlying uint16_t representation */
if (accum > INT16_MAX)
{
accum = INT16_MAX;
}
/* Save the updated count */
g_pmglobals.accum = (int16_t)accum;
/* Check the elapsed time. In periods of low activity, time slicing is
* controlled by IDLE loop polling; in periods of higher activity, time
* slicing is controlled by driver activity. In either case, the duration
* of the time slice is only approximate; during times of heavy activity,
* time slices may be become longer and the activity level may be over-
* estimated.
*/
now = clock_systimer();
if (now - g_pmglobals.stime >= TIME_SLICE_TICKS)
{
int16_t tmp;
/* Sample the count, reset the time and count, and assess the PM
* state. This is an atomic operation because interrupts are
* still disabled.
*/
tmp = g_pmglobals.accum;
g_pmglobals.stime = now;
g_pmglobals.accum = 0;
/* Reassessing the PM state may require some computation. However,
* the work will actually be performed on a worker thread at a user-
* controlled priority.
*/
(void)pm_update(tmp);
}
irqrestore(flags);
}
}
#endif /* CONFIG_PM */
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